1. Field of the Invention
The present invention relates to a backlight unit for use in, for example, a liquid crystal display apparatus, and to a liquid crystal module including this backlight unit.
2. Description of Related Art
Conventionally, there has been known a liquid crystal display apparatus including a liquid crystal module mounted in a housing. The liquid crystal module includes a liquid crystal panel and a backlight unit disposed behind the liquid crystal panel. There are two types of backlight units, edge type backlight units and direct type backlight units. For example, JP 2009-104946 A discloses a direct type backlight unit 10 as shown in FIG. 8.
The backlight unit 10 for illuminating a liquid crystal panel 11 from behind includes a plurality of straight tube lamps 12, a case 13 for accommodating the lamps 12 so as to cover the lamps from the side opposite to the liquid crystal panel 11, and a diffuser plate 16 disposed to close the case 13. In the case 13, a reflective sheet 14 is disposed on the bottom surface of the case 13, and a pair of lower supporting members 15 (only one of the pair is shown in FIG. 7) for supporting both ends of the diffuser plate 16 are disposed to overlap both ends of the lamps 12. Furthermore, an upper supporting member 17 for supporting the liquid crystal panel 11 is fixed to the case 13.
The lower supporting member 15 has an inclined inner side surface to reflect light coming from the lamps 12 and the reflective sheet 14 toward the diffuser plate 16. A reflective tape is attached to the inclined surface in some cases, but in the backlight unit disclosed in JP 2009-104946 A, the lower supporting member 15 is formed of a high reflective material. Therefore, the lower supporting member 15 itself reflects the incoming light toward the diffuser plate 16.
In the backlight unit 10 disclosed in JP 2009-104946 A, a wall portion 15a that faces the end face of the diffuser plate 16 is provided on the top surface of the lower supporting member 15, and a reflective sheet 18 is attached to the under surface of the upper supporting member 17. Therefore, light that is guided to a space surrounded by the top surface of the lower supporting member 15, the wall portion 15a, and the reflective sheet 18 by transmission through the diffuser plate 16 is multiply reflected by them, and allowed to reach the peripheral area of the liquid crystal panel 11.
With such a configuration, however, the light reflected by the top surface of the lower supporting member 15, the wall portion 15a, and the reflective sheet 18 is concentrated in the vicinity of the upper supporting member 17 in the peripheral area of the liquid crystal panel 11. As a result, a bright line appears along the edge of the upper supporting member 17 when the liquid crystal panel 11 is seen from the front side thereof.